Tennis Star Serena Williams Calls ‘Foul’ on Neck Lump: What Is a Branchial Cleft Cyst?

What are branchial arches and when do they form?

The branchial apparatus is the part of the embryo that forms various structures in the head and neck. Over time and development in the embryo, those structures migrate and form into areas of the face, ear, jaw and neck. There are three areas on the branchial arches – clefts, pouches and the arches. Clefts (groove-like structures) are located on the ectodermal side (outermost layer) versus the endodermal (inner layer), which has pouches and is where the throat is located. The central portion forms into nerves, muscles and blood vessels.

How does a branchial cyst form?

A branchial cleft cyst is a congenital anomaly where, as those structures are forming in the fetus, what usually turns into a fibrous tract, or an unidentifiable anatomic structure, actually can be a fluid-filled sac. We see them much more commonly in children, since they’re congenital (present from birth). We do see them in adults, but more commonly in younger adults. They are often there not noticed – not filled with fluid – and then they fill for whatever reason. Oftentimes the fluid comes as the result of an upper-respiratory or other infection.

So they can lie dormant for many years in the pharyngeal area until something triggers a sudden swelling?

Yes, that is correct. We don’t necessarily presume it’s a branchial cleft cyst, however, because we have to first make sure that it’s not a cystic metastasis from a cancer. That’s a much more common cystic mass in an adult than a branchial cleft cyst. Branchial cleft cyst presentation in adults, especially those outside of their 20s and even 30s, are just much less common.

What kind of fluid fills these cysts?

Typically, it’s a serous fluid. The cells within it can be inflammatory cells, such as white blood cells. If it’s not infected, the fluid is serous, which is a clear to pale yellowish fluid. It can be a little mucoid depending on the patient.

Some cysts can have a communication to the throat and would thus be termed a branchial cleft “sinus,” meaning they have a tract that communicates with the throat. A typical branchial cleft cyst is confined – without any communication to the throat or the skin.

Sometimes we see a darker fluid – brownish, dark greenish or even almost a blackish color. That fluid probably has some element of a blood component, causing the darker color. It varies.

Are there different areas along the neck in which they occur?

There have been four types of branchial cleft cysts described, as there are four branchial clefts. The most common, by far, is the second branchial cleft cyst, which generally occurs just below the angle of the lower jaw usually just anterior to (in front of) a muscle called the sternocleidomastoid. The first type is found higher up – around the parotid gland (in front of and just below the ear). The third and fourth types are lower in the neck and potentially associated with the thyroid gland. All three of those types – the first, third and fourth – are much rarer.

Is there any type that’s potentially the most dangerous?

Assuming a lesion is, in fact, a branchial cleft cyst rather than a cystic nodal metastasis from cancer, one type of cyst is not inherently more dangerous than another. They all have the risk of becoming infected.

The main issue can be the location, and the surgical treatment thereof, which can come with different levels of risk based on the structures in the area that you’re working around. The second type of branchial cleft cyst is often less risky to dissect out because the important nerves in the area are larger. Conversely, a first branchial cleft cyst can be very intimately associated with the facial nerve in the parotid gland. The facial nerve is smaller with many branches and thus surgery for a first branchial cleft cyst is associated with a different risk profile, including facial paralysis.

If a cyst has been previously infected, or especially if it’s had multiple infections, surgery to remove it will be more difficult.

In Serena Williams’ case, a surgeon removed the cyst. Is that the recommended treatment?

Recommended treatment for a branchial cleft cyst is surgical excision, which should prevent future issues with infection and allows for definitive pathologic diagnosis. Patients will often have a fine needle aspiration biopsy of the cystic mass prior to any surgery, as a minimally invasive way to try and rule out cancer. Unfortunately, the yield of cells from a needle aspiration of a cyst can be low and may not be able to make a diagnosis of benign vs. malignant.

Even if the aspiration biopsy is negative, it’s best to completely remove the cyst to confirm its pathology is consistent with a benign branchial cleft cyst. With aspiration, sometimes the cyst will shrink in size with fluid removal and a patient may believe the cyst has gone away. But it’s generally expected that the cyst will fill with fluid once again.

For the most part, when they’re found in children, they end up getting surgically treated.

Williams described her cleft cyst as being the size of a small grapefruit. Is that common?

They can be various sizes. They can be small enough that people don’t know they’re there unless they get imaging for some other reason, and a cyst is found incidentally. And then they can really expand with the fluid to various sizes. There’s not a defined “typical size.”

Is it possible that a swollen cleft cyst could later turn into cancer?

The topic of a branchial cleft cyst turning into a cancer, a so-called “branchiogenic carcinoma” is one that has been debated in medicine. It is much more likely that a cystic neck mass in an adult with cancerous cells is more likely a cystic lymph node metastasis that started as primary cancer elsewhere (like throat or thyroid) and then spread to the lymph node in the neck.

Is there anything else about branchial cleft cysts that we haven’t covered?

As a head-and-neck surgeon, by no means would we ever want anyone – other medical providers or the general population – to latch onto the notion: “I have a cyst on my neck. It’s probably just a branchial cleft cyst, so no problem.” Because the vast majority of cystic neck masses in adults are more likely to be cancer, presuming that a neck cyst is a benign branchial cleft cyst could lead to a missed or delayed cancer diagnosis. Branchial cleft cysts in adults are actually pretty rare, and any cystic neck mass should undergo complete workup.